38Talk:

Dear Frank,

Sorry to be dense, but what do you mean by "shoot lunars"? I think it has to do with determining position by scoping onto the moon and consulting star and moon charts, instead of the sun?

yrs,

John

John Bryant, Professor of English
Founding Editor, Leviathan: A Journal of Melville Studies
Consulting Editor, The Melville Society, http://melvillesociety.org/
Director, Melville Electronic Library
Director, Hofstra Digital Research Center
Mason 204, Hofstra University, Hempstead, NY 11549; Tel: 516.463.5470

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From: 38Talk@fer3.com <38Talk@fer3.com> on behalf of Frank Reed <NoReply_FrankReed@fer3.com>
Sent: Tuesday, July 1, 2014 12:01 AM
To: John L. Bryant
Subject: [38Talk] Moonlit nights before Stellwagen...

 

Stellwagen day 1 is now July 11. The night before, July 10, the Moon will be nearly full in the southeast after sunset so the deck will be very bright even without artificial lighting. The stars, alas, will be lost in the usual glare of the Moon so close to full --no Milky Way-- but moonlit nights have their charm.

For those with navigational interests, these are not great conditions for lunars (which were usually shot in daylight using the Sun as the "other body"), but not awful either. We should have about an hour to shoot lunars using Saturn and Mars as the other body. You can generate tables of predicted lunars and clear lunars very easily using tools on my web site. Paper methods are also not difficult despite the reputation of those sights. And it's not entirely un-historical to shoot lunars at anchor. This was common c.1800 since longitudes of ports might be uncertain. It's anachronistic for the Morgan's sailing life, but no matter. We can pretend that Provincetown has drifted off on its own path and needs to have its longitude double-checked.

Attached is a longitude by lunar from 1825 worked up on a blank page in one of the logbooks in Mystic Seaport's collection. Tedious, but only about twenty minutes of work...

The following night, July 11, the Moon will be rising just before sunset, as it always does at Full Moon, and it should look quite lovely. The "Moon Illusion" will be in full swing with the Moon low above the southeast horizon, and to add slightly to the effect, lunar perigee is a day later so the Moon will be larger than average even in an objective sense. Someone should arrange for a photographer a few miles away from the Morgan to the northwest with a telephoto lense.. Seriously. If it's clear, that's a photo Mystic Seaport must have!

Frank Reed
ReedNavigation.com / HistoricalAtlas.com
Conanicut Island  USA

Attached File:

(scrap-1825-full.jpg: Open and save)

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